This entrapment syndrome occurs when the common peroneal nerve is compressed along its course around the fibular head, a bony structure found on the lateral aspect of the leg just below the knee. Like the ulnar nerve entrapment, trauma often predisposes to this entrapment syndrome. Typically a single traumatic event, rather that a series of minor injuries as in ulnar neuropathy, injures the peroneal nerve. A severe blow to the side of the knee, twisting the ankle (thus stretching the nerve), and prolonged recumbency with the knee against a hard surface are all common causes of peroneal nerve injuries in this location. These patients typically complain of pain in the lower leg, numbness on the top of the foot, and foot drop.
Patients who suffer from foot drop require ankle bracing until muscle strength returns. Those who have severe pain and/or weakness do not get better after a period of observation are candidates for decompressive surgery.
Figure 1. Intraoperative photograph demonstrating the incision used to perform a peroneal nerve decompression at the fibular head. The incision follows the course of the nerve across this region. The fibular head is marked by the black circle.
Figure 2. Magnified intraoperative photograph showing the common peroneal nerve (C) and its branches after decompression across the fibular head (F). Visible branches include the articular branch (1), deep division (2), superficial division (3), and branch to the peroneus longus muscle (4).